Expérimental
Low temperature helium 4 is a model system for the study of condensed matter. The Quantum Liquid and Solid Group of Laboratoire Kastler Brossel has developed experimental tools to produce and characterize metastable negative pressure states of superfluid helium-4 at about 1 K. The aim of the internship is to develop a Brillouin spectrometer (sound velocity-meter) based on a single pulsed laser capable of measuring not only the speed of sound but also the attenuation of sound in superfluid helium-4.